I've been teaching on Skype for a few months--I took over my friend's classes when she got sick. She was teaching Russians for an online Russian company.

My set-up is basic: Logitech C210 camera and a simple Logitech headset. It has worked well in the classes I have taught so far. My image and sound were as good as the other teachers in that company. And they have been good enough for my editing meetings (my main job)--as good as those on the other end.

However, the other day I did have a Skype meeting with new colleague, and his picture was much clearer and brighter than your average bear's. I asked him about it, and he said he has carefully chosen the lighting in his room and calibrated it, has a white screen for a backdrop, and a more expensive HD camera. He also has a more expensive headset--though it was his superior image quality, rather than audio, that really impressed me. He also teaches--in Japan in his case--and he implied that this level of quality was needed.

I'm about to teach Koreans online (in groups, possibly in academies/schools). I'm a bit of a newbie with Skype and webcams, aside from my previously mentioned teaching. I'd appreciate any advice I could get. Koreans, being Koreans, are going to be 3000% more serious about all this than Russians. I'm wondering if I need better image quality. If so, is an HD camera de rigeur here? Any recommendations? What about lighting (I'll mostly be teaching at night) and backdrop?

I was in Korea 3 years ago and had difficulty locating a good high quality web cam. The best I found was in the Microsoft range, I couldn't get any good quality Logitech cameras (I think 1.3mp was the best I could find).

1.3 is quite low/average quality nowadays. However, a lot of Korean computers have basic webcams built in so 1.2/1.3 seems to be the average quality in Korea and cheap webcams seem to be common.

Provided your computer can deal with it (my own logitech webcam - a few years old - used to slow down my old computer) and you have no problem with streaming to your students then you should be able to source a better webcam for 50-60. Expermenting with lighting can also yield cost-efficient benefits - sometimes closing the curtains and experimenting with a lamp can work. Keep in mind that having too high a quality picture can cause problems if the connection to your students isn't phat enough - audio will lag, image might jitter etc.

If so, is an HD camera de rigeur here?

I'd say no, but I haven't done any online teaching.

What about lighting (I'll mostly be teaching at night) and backdrop?

If you're being employed then your employer should probably specify these conditions.

My set-up is basic: Logitech C210 camera and a simple Logitech headset. It has worked well in the classes I have taught so far. My image and sound were as good as the other teachers in that company. And they have been good enough for my editing meetings (my main job)--as good as those on the other end.

There is the old saying you get what you paid for.
The C210 was retail 30 usd. So no HD quality there.

If you want I have a much better cam I've been thinking about selling.
The one I have is the QuickCam Orbit auto-focus.
Retail was 130 usd.
There are several things I like on this model.
720 HD quality others can see you at.
Motorized tracking!
Carl Zeiss lens.
It also has two different stands.
You set it up to watch your home while you are away and the motorized feature is perfect for it!
I would let it go 75,000.